Asciinema: Terminal Recording Done Right (with Marcin Kulik)

I have a theory that only bad projects get finished — good ones keep finding new things to do. Asciinema is a case in point. What started as a way to share terminal sessions with friends has, over 14 years, grown into a full suite of tools covering recording, hosting, playback, and live streaming — and been rebuilt multiple times along the way. So what does it actually take to record and replay a terminal session faithfully in a browser?

Joining us for this conversation is Marcin Kulik, Asciinema's creator. The project's architecture has passed through almost every interesting corner of software engineering: a Python recorder built around pseudo-terminals (PTY), a ClojureScript terminal emulator for the browser that hit performance limits with immutable data structures and garbage collection pressure, a move to Rust compiled to WebAssembly, a Go experiment that didn't last, and a new Rust CLI for concurrent live streaming backed by an Elixir/Phoenix server that calls Rust code via NIFs. The same Rust terminal emulator library now powers all three components — the browser player, the server, and the CLI.

If you've ever looked at those terminal animations embedded in a README and wondered what's underneath them, or if you're interested in how a passionate open-source developer navigates 14 years of language changes and rewrites, this conversation has plenty to offer.

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Asciinema: https://asciinema.org

Asciinema Docs: https://docs.asciinema.org

Asciinema CLI (GitHub): https://github.com/asciinema/asciinema

Asciinema Player (GitHub): https://github.com/asciinema/asciinema-player

Asciinema Server (GitHub): https://github.com/asciinema/asciinema-server

AVT - Rust terminal emulator library: https://github.com/asciinema/avt